Water Intake Calculator
Free Water Intake Calculator to estimate your daily water intake based on your weight, activity level, and lifestyle for proper hydration.
What does this Water Intake Calculator do?
This calculator estimates a baseline daily water target using a common weight-based guideline, then adds an allowance for exercise since sweating increases fluid needs.
The formula
Base intake (ml) = weight (kg) × 35, plus an additional allowance based on daily exercise duration (roughly 350 ml extra per 30 minutes of exercise).
Step-by-step example
For someone weighing 68 kg who exercises 30 minutes a day: base = 68 × 35 = 2,380 ml, plus 350 ml for exercise = 2,730 ml total, or roughly 2.7 liters — about 11 glasses of 250 ml each.
Tips & common mistakes
- This is a general guideline, not a medical prescription — actual needs vary with climate, diet (especially sodium intake), pregnancy, and certain health conditions.
- Water from food (fruits, vegetables, soups) also contributes to hydration — this calculator estimates fluid from drinking specifically.
- Thirst is a reasonably reliable signal for most healthy adults; use this number as a rough target rather than a strict daily quota.
Frequently asked questions
No — it's a baseline estimate from body weight and exercise alone. Hot weather, high-sodium diets, and illness all increase fluid needs beyond this estimate.